Cole Bubbles 1e
The original theory behind Dandridge M. Cole’s “bubbleworld” habitat was to quickly create a hollow sphere by the expansion from ﬂash evaporation of water inside a cavity dug at the center of a metallic asteroid. In practice, this turned out to be extremely difficult because few asteroids were homogenous enough to withstand this process without cracking along impurities. On top of that, the energy expenditure to soften the asteroid into an elastic state and ﬂash boil the water are immense. Instead, most habitats called Cole bubbles are created by a more controlled method. A suitable metallic asteroid is encapsulated in a thin polymer shell inflated to the desired radius with carbon monoxide at low pressure. The entire collection is heated until the nickel and iron in the asteroid begin to react with the CO gas. By keeping the shell at a constant temperature and with transport assisted by nanoparticle catalysts, the nickel alloys will deposit evenly on the interior of the shell until the heat is cut off and the reaction stops. The fabrication shell can either be kept in place as a protective coating or recycled for other uses. Any remaining carbon monoxide, metal ore, volatiles, and silicates serve as feedstock for synthesizing industrial materials for the Cole habitat’s internal systems. These can include composites and lubricants made from hydrocarbons and ceramic-metal hybrids. Like anywhere else, as many of the local resources are utilized as possible. Cole bubbles left in microgravity are popular amongst neo-avians and transhumans adapted permanently for life in zero g because they can literally ﬂy from one point in the habitat to any other, so long as any obstructions are accounted for. Water-breathing species share this affinity as well, though their habs must have significantly thicker shells to hold the water pressure. Cole habitats can also be spun for artiﬁcial gravity; the centrifugal effect proportionally decreases the closer one gets to the poles along the axis of rotation. There is no functional difference between these habitats and Bernal spheres. Only the construction method is different. Most residents of spun Cole bubbles are in the central third of the sphere where gravity variation is the least. The remaining two-thirds are evenly divided into park and agricultural space and windows near the poles for mirrors to reﬂect in ambient light. Some enterprising developers have ﬁgured out how to control the deposition process such that the bubble is shaped more like a lozenge, thus increasing the internal area spun to the desired speed. The deposition rate is kept the same along the oblong substrate by using nanomachine swarms to induce and control a gradient in the catalyst concentrations in the CO gas. Because Cole bubbles are fashioned from large metallic asteroids, they are predominately found in the Belt (the icy asteroids found elsewhere being unusable). Cole bubbles can be quite large, easily over 10 kilometers in diameter, and so are capable of supporting hundreds of thousands or even several million people. Spaceports are located at the bubble’s axis points, taking advantage of the zero g there.